JPH0840946A - Production of dialkyltetralin - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a raw material, etc., for a polymeric material in high conversion rate and selectivity without causing the elution, etc., of a catalyst by cyclizing an alkenylbenzene with a solid superstrong acid as a catalyst. CONSTITUTION:This method for producing a dialkyltetralin is to cyclize an alkenylbenzene of the formula (R1 is H, ethyl, etc.; R2 is H or methyl; R3 is CH=CH-CH3 or CH2-CH=CH2) (e.g. o-tolyl-2-pentene) in the presence of a solid superstrong acid or the solid superstrong acid containing a group VIII element of the periodic table, preferably at normal temperatures to 150 deg.C of eactional temperature under normal pressure to 20kg/cm<2> of reactiona1 pressure. Furthermore, the solid superstrong acid is preferably obtained by mixing a treating agent containing sulfate radicals such as 0.1-5N sulfuric acid in an oxide or a hydroxide of zirconium, titanium, etc., and then baking the resultant mixture at 500-650 deg.C in an oxidizing atmosphere for 0.5-10hr. The cyclizing reaction is preferably carried out in the presence of an inert gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a dialkyltetralin by subjecting an alkenylbenzene to a cyclization reaction.

[0002]

BACKGROUND OF THE INVENTION Dialkyltetralin has a wide range of uses as a raw material for polymer materials and pharmaceutical materials. In particular, 1,5-dimethylnaphthalene obtained by dehydrogenating 1,5-dimethyltetralin is 2,6-dimethylnaphthalene which is a raw material of industrially useful 2,6-naphthalenedicarboxylic acid through an isomerization step. Can be converted to.

By the way, dimethylnaphthalene exists in refinery streams derived from petroleum or coal as a mixture of isomers that is difficult and expensive to separate. Therefore, a specific dimethylnaphthalene alone,
Alternatively, there is a long felt need for a technique for producing it as a mixture with another one or two specific isomers.

One promising method is to catalytically cyclize one or more alkenylbenzenes to their corresponding dialkyltetralins and then dehydrogenate this cyclized product to its corresponding dialkylnaphthalene. .
Such a dialkylnaphthalene, for example, 1,5-dimethylnaphthalene, becomes a mixture of only three kinds of 1,6-isomer and 2,6-isomer by isomerization, and easily reacts with 2,6-dimethylnaphthalene.
-Dimethylnaphthalene can be separated and purified.

On the other hand, as a method for synthesizing dimethylnaphthalene from alkenylbenzene, there has been proposed a method of contacting at a temperature of 100 to 350 ° C. using a solid phosphoric acid catalyst (Japanese Patent Publication No. 50-12430). But,
In this method, tetralin selectivity is high, and a relatively stable catalytic activity is obtained, but the product is contaminated due to the eluted phosphoric acid component, or a device made of an expensive material to prevent device corrosion There is a problem in that the use of is forced.

Further, a method using a solid acid such as silica / alumina, silica / magnesia or silica / alumina / zirconia as a catalyst (USP 3,244,758, 3,773).
5,496, 3,775,497, 3,77
5,498 and 3,775,500) have been proposed. Although all of these showed high conversion, the selectivity of the target product was low, which was not always satisfactory.

The present invention solves the above-mentioned problems of the prior art and provides a method for producing a dialkyltetralin from alkenylbenzene which does not elute a catalyst and has a high conversion and a high selectivity of a target product. To aim.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and found that in the presence of a solid superacid or a solid superacid containing an element of Group VIII of the periodic table. Therefore, it was found that the reaction of alkenylbenzene under mild reaction conditions does not cause problems such as elution of the catalyst, and moreover dialkyltetralin is highly selectively produced, and the present invention has been proposed. It was

That is, the present invention is represented by the general formula (1) in the presence of a solid superacid or a solid superacid containing a Group VIII element of the periodic table (hereinafter simply referred to as a Group VIII element). The gist is a method for producing dimethyltetralin by catalytic cyclization of alkenylbenzene.

[0010]

Embedded image

In the formula (1), R ₁ is one member selected from the group consisting of hydrogen, methyl, ethyl and isopropyl, and R ₂ is 1 selected from the group consisting of hydrogen and methyl.
A member, _{R 3} is -CH = CH-CH ₃ and -CH ₂
An alkenyl group selected from the group consisting of —CH═CH ₂ .

The present invention will be described in detail below. The starting material of the present invention is a substituted benzene (alkenylbenzene) having an alkenyl group (R ₃ ) represented by the general formula (1). As an example, o-tolyl-2-pentene, o
-Tolyl-1-pentene, m-tri-2-pentene, m
-Tolyl-1-pentene and the like can be mentioned.

In the present invention, these substituted benzenes having an alkenyl group react in the presence of the above catalyst, and the substituents bond with the benzene ring to form a tetralin ring.

The above-mentioned starting materials may be used alone or in the form of a mixture of alkenylbenzenes, or may be diluted with an organic solvent before use. Examples of the solvent include aromatic hydrocarbons such as benzene and toluene, and saturated aliphatic hydrocarbons such as heptane and hexane.

The catalyst used in the present invention is called a solid superacid, and is made of an oxide or hydroxide of zirconium, titanium, aluminum, hafnium, silicon, germanium, tin, magnesium, calcium or the like containing a sulfate group. Refers to something.

A solid superacid is generally defined as an acid stronger than 100% sulfuric acid ("superacid / superbase", Kozo Tabe,
Ryoji Noyori, Kodansha Scientific (198
0)). On the other hand, the solid acid strength can be determined by a titration method using a Hammett indicator in a benzene solvent. In the present invention, the Hammett indicator has a PKa value of −
5.6 or less, preferably sulfuric acid PKa value-11.
A solid superacid is less than 93, that is, higher than the acid strength of sulfuric acid.

As a method for preparing this catalyst, generally, a method is used in which a treating agent containing a sulfate group is mixed with the above oxide or hydroxide, followed by calcination.

The treating agent containing the above-mentioned sulfate group usually contains 0.01 to 10 N, preferably 0.1 to 5 N sulfuric acid, or 0.1 to 10 molar ammonium sulfate as a catalyst (as described above). (Oxide or hydroxide) 1 to 10 times amount is used per weight. In addition to the above, a treating agent that produces sulfate during the baking treatment, for example, hydrogen sulfide, sulfurous acid gas or the like may be used, and the amount of these treating agents to be used is the above sulfuric acid, ammonium sulfate or the like. The amount may be about the same as the amount of sulfate radical in some cases.

The firing after mixing the above-mentioned treating agent is 4
It is necessary to perform a stabilization treatment by baking at 50 to 800 ° C., preferably 500 to 650 ° C., in an oxidizing atmosphere for 0.5 to 10 hours. If this calcination stabilization treatment is carried out in a reducing atmosphere, the catalytic activity will be significantly reduced due to a change in the binding state of sulfate radicals or a cause that is considered to be due to reductive decomposition.

After such calcination, it can be used as it is as a catalyst for the cyclization reaction in the present invention, but a catalyst containing a Group VIII element can also be used. The introduction of the Group VIII gold element may be carried out before the addition of the sulfate group, or after the introduction thereof, without any problem.

Group VIII elements include platinum, nickel, iron,
At least one metal selected from the group consisting of cobalt, ruthenium, rhodium, palladium, osmium, and iridium or a compound thereof is used, and each of them is treated by a usual impregnation method, an ion exchange method, or the like, after the above firing. Can be introduced (supported) into the solid superacid (carrier). Taking platinum as an example, it can be supported in the form of an aqueous solution of chloroplatinic acid, a tetraammine platinum complex or the like.

The content of the Group VIII metal is preferably 0.1 to 10% by weight, more preferably 0.
It is 5 to 5% by weight.

In the present invention, when the above alkenylbenzene cyclization reaction is carried out using the above catalyst, the reaction system is not particularly limited and may be a batch process, a continuous process or the like.
Either can be adopted. The reactor is not particularly limited, and any one of moving bed, fixed bed, fluidized bed, etc. can be adopted.
However, from the viewpoint of operability, a fixed bed flow type is preferable.

The amount of the catalyst used is 0.1 to alkenylbenzene in the case of the batch method.
10% by weight, preferably 0.3-3% by weight, is suitable. However, if desired, the amount may be larger or smaller than this, and in the case of carrying out other reaction systems, this may be used as a guide and may be appropriately determined. The reaction temperature is -5
The temperature is 0 ° C to 300 ° C, preferably 0 to 200 ° C, and more preferably room temperature to 150 ° C. Reaction pressure is normal pressure to 10
0 kg / cm ² , preferably atmospheric pressure to 50 kg / cm ² ,
More preferably, the atmospheric pressure is 20 kg / cm ² . And in the case of the fixed bed flow system, WHSV is 0.001-1.
00 / h, preferably 0.01 to 50 / h, and more preferably 0.05 to 20 / h.

In the present invention, it is preferable to coexist with an inert gas in order to prevent the hydrogen produced by the cyclization reaction (with dehydrogenation) from being accompanied by the reaction for hydrogenating the alkenylbenzene as the raw material. As this inert gas,
Nitrogen, steam, carbon dioxide, etc. may be mentioned.

[0026]

【Example】

[Preparation of catalyst] (1) Preparation of zirconia solid acid catalyst: 900 parts by weight of commercially available zirconium oxychloride was added to 70 parts of pure water.
It was dissolved in 100 parts by weight, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The generated precipitate was aged overnight and filtered, washed and dried to obtain 300 g of Zr (OH) ₄ white powder.

This white powder was introduced into 650 parts by weight of 1N sulfuric acid, excess sulfuric acid was filtered off, and then dried at 110 ° C. to obtain 6
Calcination was carried out at 00 ° C. for 3 hours to obtain catalyst A. The solid acid strength of catalyst A was measured by a titration method using a Hammett indicator in a benzene solvent, and the results are shown in Table 1.

(2) Preparation of titania solid acid catalyst: 500 parts by weight of commercially available titanium tetrachloride is dissolved in 800 parts by weight of pure water, and an appropriate amount of aqueous ammonia is added to the solution to adjust the pH to 1
It was set to 0. The precipitate formed is aged overnight, filtered,
150 parts by weight of white powder of Ti (OH) ₄ was obtained.

This white powder was introduced into 500 parts by weight of a 1 molar aqueous ammonium sulfate solution, the excess aqueous ammonium sulfate solution was filtered, and then dried at 110 ° C. to 600 ° C.
Calcination was performed for 3 hours to obtain a catalyst B. For catalyst B,
The solid acid strength was measured in the same manner as in (1), and the results are shown in Table 1.

(3) Preparation of solid alumina acid catalyst: 700 parts by weight of commercially available aluminum nitrate is dissolved in 950 parts by weight of pure water, and an appropriate amount of aqueous ammonia is added to this to adjust pH.
Was set to 10. The produced precipitate was aged overnight, filtered and dried to obtain 220 parts by weight of a white powder of Al (OH) ₃ .

This white powder was introduced into 500 parts by weight of a 2 molar aqueous ammonium sulfate solution, the excess aqueous ammonium sulfate solution was filtered, and then dried at 110 ° C. and 600 ° C.
Calcination was performed for 3 hours to obtain a catalyst C. For catalyst C,
The solid acid strength was measured in the same manner as in (1), and the results are shown in Table 1.

(4) Preparation of platinum-containing zirconia solid acid catalyst: 900 parts by weight of commercially available zirconium oxychloride was added to 70 parts of pure water.
It was dissolved in 100 parts by weight, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The produced precipitate was aged overnight and filtered, washed and dried to obtain 300 parts by weight of Zr (OH) ₄ white powder.

This white powder was impregnated with an aqueous solution of chloroplatinic acid (concentration of 0.5 parts by weight of platinum metal based on 100 parts by weight of carrier << white powder of Zr (OH) ₄ >>). Then, dry it at 110 ° C for a whole day and night.
Introduced into 0 parts by weight and filtered off excess sulfuric acid, then 600
Calcination was performed for 3 hours to obtain a catalyst D. With respect to the catalyst D, the solid acid strength was measured in the same manner as in (1), and the results are shown in Table 1.

(5) Preparation of titania solid acid catalyst containing platinum: 500 parts by weight of commercially available titanium tetrachloride was dissolved in 800 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added thereto to adjust pH to 1.
It was set to 0. The formed precipitate was aged overnight, filtered and dried to obtain 150 parts by weight of a white powder of Ti (OH) ₄ .

This white powder was converted into an aqueous solution of chloroplatinic acid (concentration of 0.5 parts by weight in terms of platinum metal based on 100 parts by weight of carrier << white powder of Ti (OH) ₄ >>). Impregnation, drying at 110 ° C., introduction into 500 parts by weight of a 1 molar aqueous ammonium sulfate solution, filtration of excess ammonium aqueous solution, drying at 110 ° C., 600
Calcination was performed for 3 hours to obtain a catalyst E. The solid acid strength of catalyst E was measured in the same manner as in (1), and the results are shown in Table 1.

(6) Preparation of platinum-containing alumina solid acid catalyst: 700 parts by weight of commercially available aluminum nitrate was dissolved in 950 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added thereto to adjust pH.
Was set to 10. The formed precipitate was aged overnight, filtered and dried to obtain 220 parts by weight of a white powder of Al (OH) ₂ .

This white powder was made into an aqueous solution of chloroplatinic acid (concentration of 0.5 parts by weight in terms of platinum metal based on 100 parts by weight of carrier << white powder of Al (OH) ₂ >>). Impregnation, drying at 110 ° C., introduction into 500 parts by weight of a 2 molar aqueous ammonium sulfate solution, filtration of excess ammonium hydroxide solution, drying at 110 ° C., 600 ° C.
Calcination was performed for 3 hours to obtain a catalyst F. For catalyst F,
The solid acid strength was measured in the same manner as in (1), and the results are shown in Table 1.

(7) Preparation of Hafnium Oxide Solid Acid Catalyst: 100 parts by weight of commercially available hafnium oxide was introduced into 400 parts by weight of ammonium sulfate having a molar concentration of 1, and the excess ammonium sulfate aqueous solution was filtered and then dried at 110 ° C. to obtain 600
Calcination was performed for 3 hours to obtain a catalyst M. The solid acid strength of the catalyst M was measured in the same manner as in (1), and the results are shown in Table 2.

(8) Preparation of silica solid acid catalyst: 100 parts by weight of commercially available water glass was introduced into 400 parts by weight of ammonium sulfate having a molar concentration of 1, and excess ammonium sulfate aqueous solution was filtered, followed by drying at 110 ° C. and 600 ° C. In 3
Firing was performed for a time to obtain a catalyst N. For catalyst N,
The solid acid strength was measured in the same manner as in (1), and the results are shown in Table 2.

(9) Preparation of solid oxide catalyst of tin oxide: 100 parts by weight of commercially available stannous chloride was introduced into 400 parts by weight of ammonium sulfate having a molar concentration of 1, and excess ammonium sulfate aqueous solution was filtered and dried at 110 ° C. , 600 ° C
Calcination was performed for 3 hours to obtain catalyst O. For catalyst O,
The solid acid strength was measured in the same manner as in (1), and the results are shown in Table 2.

(10) Preparation of Nickel-Containing Zirconia Solid Acid Catalyst: A nickel-containing zirconia solid acid catalyst was prepared in the same manner as in (4), except that an aqueous nickel nitrate solution was used instead of the chloroplatinic acid aqueous solution. Got The solid acid strength of the catalyst P was measured in the same manner as in (1), and the results are shown in Table 2.

(11) Preparation of Ruthenium-Containing Zirconia Solid Acid Catalyst: A ruthenium-containing zirconia solid acid catalyst was prepared in the same manner as in (4) except that a ruthenium nitrate aqueous solution was used instead of the chloroplatinic acid aqueous solution. Got The solid acid strength of catalyst Q was measured in the same manner as in (1), and the results are shown in Table 2.

(12) Preparation of rhodium-containing zirconia solid acid catalyst: A rhodium-containing zirconia solid acid catalyst was prepared in the same manner as in (4) except that an aqueous rhodium chloride solution was used instead of the chloroplatinic acid aqueous solution, and the catalyst R Got The solid acid strength of the catalyst R was measured in the same manner as in (1), and the results are shown in Table 2.

(13) Preparation of Palladium-Containing Zirconia Solid Acid Catalyst: A rhodium-containing zirconia solid acid catalyst was prepared in the same manner as in (4) except that an aqueous palladium chloride solution was used instead of the chloroplatinic acid aqueous solution. Got The solid acid strength of the catalyst S was measured in the same manner as in (1), and the results are shown in Table 2.

(14) Preparation of osmium-containing zirconia solid acid catalyst: An osmium-containing zirconia solid acid catalyst was prepared in the same manner as in (4) except that an osmic acid aqueous solution was used instead of the chloroplatinic acid aqueous solution, and the catalyst T Got With respect to the catalyst T, the solid acid strength was measured in the same manner as in (1), and the results are shown in Table 2.

(15) Preparation of Iridium-Containing Zirconia Solid Acid Catalyst: An iridium-containing zirconia solid acid catalyst was prepared in the same manner as in (4) except that an iridium chloride aqueous solution was used instead of the chloroplatinic acid aqueous solution. Got The solid acid strength of the catalyst U was measured in the same manner as in (1), and the results are shown in Table 2.

In Table 1, G and J are selected from the catalysts prepared and used in Comparative Examples described below, and the solid acid strength is measured in the same manner as in (1). The results are also shown. .

In Tables 1 and 2, the column of pKa value of the Hammett indicator marked with * shows the result of the color change point judgment in the benzene solvent, "+" means "color change" and "±" means "color change". "Slightly discolored" and "-" mean "no discoloration". The Hammett indicator used was "dicin namalacetone" at pKa value "-3.0", "benzalacetophenone" at "-5.6", "anthraquinone" at "-8.2",
"-11.4" means "paranitrotoluene", "-1"
2.7 "is" paranitrochlortoluene ".

[0049]

[Table 1]

[0050]

[Table 2]

Example 1: Using a fixed bed flow reactor, the catalyst A obtained above
Of 10 g of o-tolyl-2-pentene in the presence of 2 g of
% Toluene solution was fed at WHSV = 0.2 / h (relative to alkenylbenzene). Reaction temperature is 30
℃, the reaction pressure is normal pressure, nitrogen gas as a carrier 20
It was supplied at cc / min. The results are shown in Table 3. The conversion rate and the selectivity were set as follows.

[0052]

[Equation 1]

Examples 2 to 9: The reaction was performed in the same manner as in Example 1 except that the catalyst and the reaction temperature were changed as shown in Table 3, and the results are shown in Table 3.

[0054]

[Table 3]

Examples 10 to 18: The reaction was performed in the same manner as in Example 1 except that the catalyst and the reaction temperature were changed as shown in Table 4, and the results are shown in Table 4.

[0056]

[Table 4]

Examples 19 to 24: The reaction was carried out in the same manner as in Example 1 except that the reaction pressure, WHSV, catalyst and reaction temperature were changed as shown in Table 5, and the results are shown in Table 5.

[0058]

[Table 5]

Comparative Example 1: 900 parts by weight of commercially available zirconium oxychloride was dissolved in 7,000 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The precipitate formed is aged overnight and filtered, washed and dried to obtain Zr.
900 parts by weight of a white powder of (OH) ₄ was obtained.

The reaction was carried out in the same manner as in Example 1 except that this white powder was calcined at 600 ° C. for 3 hours and used as a catalyst (catalyst G), and the results are shown in Table 6.

Comparative Example 2: 500 parts by weight of commercially available titanium tetrachloride was dissolved in 800 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The formed precipitate was aged overnight, filtered, and dried to obtain a white powder of Ti (OH) ₄ 15
0 parts by weight were obtained.

Reaction was carried out in the same manner as in Example 1 except that a catalyst (catalyst H) was obtained by calcining this white powder at 600 ° C. for 3 hours, and the results are shown in Table 6.

Comparative Example 3: Commercially available aluminum nitrate 700
Part by weight was dissolved in 950 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The produced precipitate was aged overnight, filtered and dried to obtain 220 parts by weight of a white powder of Al (OH) ₃ .

Reaction was carried out in the same manner as in Example 1 except that a catalyst (catalyst I) was obtained by calcining this white powder at 600 ° C. for 3 hours, and the results are shown in Table 6.

Comparative Example 4: 900 parts by weight of commercially available zirconium oxychloride was dissolved in 7,000 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The precipitate formed is aged overnight and filtered, washed and dried to obtain Zr.
300 parts by weight of white powder of (OH) ₄ was obtained.

This white powder was impregnated with an aqueous solution of chloroplatinic acid (concentration of 0.5 parts by weight in terms of platinum metal based on 100 parts by weight of carrier << white powder of Zr (OH) ₄ >>). Then, dry it at 110 ℃ for 24 hours and then at 600 ℃ for 3 days.
What was calcined for a time was used as a catalyst (catalyst J) and the reaction temperature was 1
The reaction was performed in the same manner as in Example 1 except that the temperature was 30 ° C., and the results are shown in Table 6.

Comparative Example 5: 500 parts by weight of commercially available titanium tetrachloride was dissolved in 800 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The formed precipitate was aged overnight, filtered, and dried to obtain a white powder of Ti (OH) ₄ 15
0 parts by weight were obtained.

This white powder was made into an aqueous solution of chloroplatinic acid (concentration of 0.5 parts by weight in terms of platinum metal based on 100 parts by weight of carrier << white powder of Ti (OH) ₄ >>). The reaction was performed in the same manner as in Comparative Example 4 except that the catalyst (catalyst K) was impregnated, dried at 110 ° C., and calcined at 600 ° C. for 3 hours, and the results are shown in Table 6.

Comparative Example 6: Commercially available aluminum nitrate 700
Part by weight was dissolved in 950 parts by weight of pure water, and an appropriate amount of aqueous ammonia was added to adjust the pH to 10. The produced precipitate was aged overnight, filtered and dried to obtain 220 parts by weight of a white powder of Al (OH) ₃ .

This white powder was made into an aqueous solution of chloroplatinic acid (an aqueous solution having a concentration such that it would be 0.5 parts by weight in terms of platinum metal based on 100 parts by weight of the carrier << white powder of Al (OH) ₃ >>). The reaction was performed in the same manner as in Comparative Example 4 except that the catalyst (catalyst L) was impregnated, dried at 110 ° C., and calcined at 600 ° C. for 3 hours, and the results are shown in Table 6.

Comparative Example 7: Commercially available silica alumina (SiO 2
₂ / Al ₂ O ₃ = 20) was used as a catalyst as it was, and the reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 300 ° C., and the results are shown in Table 6.

Comparative Example 8: Commercially available H-type mordenite (Si
O ₂ / Al ₂ O ₃ = 10) was used as a catalyst as it was, and the reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 240 ° C., and the results are shown in Table 6.

Comparative Example 9: Commercially available H-type Y-type zeolite (S
The reaction was performed in the same manner as in Example 1 except that iO ₂ / Al ₂ O ₃ = 5) was used as a catalyst and the reaction temperature was 200 ° C. The results are shown in Table 6.

Comparative Example 10: Commercially available super stable hydrogen form crystalline aluminosilicate zeolite Y (SiO ₂ / Al ₂ O ₃
= 20, unit cell size = 24.25Å) was used as a catalyst as it was, and the reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 180 ° C. The results are shown in Table 6.

[0075]

[Table 6]

From the above results, it can be seen that by incorporating a sulfate group into the catalyst, both show high conversion and selectivity, and the solid superacid catalyst is effective for this reaction.
Further, even when compared with other catalyst systems (Comparative Examples 7 to 10), the method of the present invention can be carried out under mild reaction conditions (reaction temperature, reaction pressure, etc.) and, at the same time, is a by-product. You can see that there are few.

[0077]

As described in detail above, according to the present invention,
Since the reaction conditions may be mild, problems such as catalyst elution do not occur, and the generation of by-products is small, and as a result of these,
It is possible to provide a method for producing a dialkyltetralin from alkenylbenzene, which is free from problems such as product stains and equipment corrosion. In addition, the production method of the present invention has a high conversion rate of alkenylbenzene as a raw material and a high selectivity rate of dialkyltetralin which is a target product, and its industrial significance is extremely high.

Claims (2)

[Claims] 1. A dialkyltetralin which comprises cyclizing an alkenylbenzene represented by the general formula (1) in the presence of a solid superacid or a solid superacid containing an element of Group VIII of the periodic table. Manufacturing method. Embedded image In the formula (1), R ₁ is one member selected from the group consisting of hydrogen, methyl, ethyl and isopropyl, R ₂ is one member selected from the group consisting of hydrogen and methyl, and R ₃
-CH they are = CH-CH ₃ and _-CH 2 -CH = CH ₂
Is an alkenyl group selected from the group consisting of 2. The solid strong acid is a pKa of a Hammett indicator.
2. At least one selected from the group consisting of a metal oxide containing a sulfate group and a metal hydroxide having a value (in a benzene solution) <-11.93.
A method for producing the dialkyltetralin described.